Optical correlator using spatial light modulator illumination

Abstract

An optical correlator ( 10 ) that uses a spatial light modulator ( 11 ) to illuminate a pattern of on and off pixels into a length of an optical fiber ( 12 ). The spatial light modulator ( 11 ) is optically coupled to the length of fiber ( 12 ) so that the illumination enters the fiber along that length. The optical fiber ( 12 ) also carries light representing a bitstream of data. At the optical fiber, the illumination from the spatial light modulator interacts with the illumination of the optical bitstream. A detector ( 14 ) is optically coupled to the same length of fiber ( 12 ) and detects the resulting optical response to determine if a correlation exists.

What is claimed is:  
     
       1. An optical correlator, comprising: 
       a spatial light modulator having at least one row of pixel generating elements, said at least one row operable to generate a one-dimensional pattern of on or off illumination;  
       an optical guide optically coupled to said at least one row such that a length of the optical guide may receive the illumination from that row, the optical guide operable to transmit a bitstream of optical information; and  
       a detector placed along the same length of the optical guide, optically linked to the optical guide such that the detector is operable to receive illumination from the length of optical guide representing the interaction at the guide between the bitstream and the illumination from the spatial light modulator.  
     
     
       2. The correlator of  claim 1 , wherein the optical coupling is between the guide and the detector is linear such that the interaction provides illumination proportional to the combined intensities of the bitstream and the illumination from the spatial light modulator. 
     
     
       3. The correlator of  claim 1 , wherein the optical coupling between the guide and the detector is nonlinear such that the interaction provides significant output illumination only above a threshold illumination. 
     
     
       4. The correlator of  claim 1 , wherein the optical coupling between the spatial light modulator and the guide is achieved by coating the guide. 
     
     
       5. The correlator of  claim 1 , wherein the optical coupling between the spatial light modulator and the guide is achieved by immersing the guide in a fluid. 
     
     
       6. The correlator of  claim 1 , wherein the optical coupling between the spatial modulator and the guide modifies the index of refraction of the guide. 
     
     
       7. The correlator of  claim 1 , wherein the optical coupling between the spatial light modulator and the guide causes an interaction of light within the guide. 
     
     
       8. The correlator of  claim 1 , wherein the optical coupling between the spatial light modulator and the guide causes an interaction of light at the surface of the guide. 
     
     
       9. The correlator of  claim 1 , wherein the optical coupling between the detector and the guide is achieved by coating the guide. 
     
     
       10. The correlator of  claim 1 , wherein the optical coupling between the detector and the guide is achieved by immersing the guide in a fluid. 
     
     
       11. The correlator of  claim 1 , wherein the optical coupling between the detector and the guide modifies the index of refraction of the guide. 
     
     
       12. The correlator of  claim 1 , wherein the optical coupling between the detector and the guide causes an interaction of light within the guide. 
     
     
       13. The correlator of  claim 1 , wherein the optical coupling between the detector and the guide causes an interaction of light at the surface of the guide. 
     
     
       14. The correlator of  claim 1 , wherein a single optical coupling couples the spatial light modulator and the guide and the detector and the guide. 
     
     
       15. The correlator of  claim 1 , wherein the optical guide is an optical fiber. 
     
     
       16. The correlator of  claim 1 , wherein the spatial light modulator is a digital micro mirror device. 
     
     
       17. The correlator of  claim 1 , wherein the spatial light modulator is a liquid crystal device. 
     
     
       18. The correlator of  claim 1 , wherein the spatial light modulator has multiple rows. 
     
     
       19. The correlator of  claim 18 , wherein the light guide is a plate light guide. 
     
     
       20. A method of correlating a bitstream carried by an 
       optical guide with a target pattern, comprising the steps of:  
       illuminating the optical guide with a pattern of on and off illumination generated by a spatial light modulator;  
       receiving the illumination from the spatial light modulator into a length of the optical guide; and  
       detecting the interaction, at the optical guide, of the illumination from the spatial light modulator and the bitstream.  
     
     
       21. The method of  claim 20 , wherein the receiving step is performed by using a coating that optically couples the optical guide to the spatial light modulator. 
     
     
       22. The method of  claim 20 , wherein the detecting step is performed by using a coating that optically couples a detector to the optical guide. 
     
     
       23. The method of  claim 20 , wherein the detecting step is performed by detecting a nonlinear response of an optical coupling of the spatial light modulator to the optical guide. 
     
     
       24. The method of  claim 20 , wherein the pattern is generated by a single row of the spatial light modulator and the guide carries a single bitstream. 
     
     
       25. The method of  claim 20 , wherein the pattern is a generated by an SLM array and the guide carries multiple bitstreams.